1. Technical Field
The present invention relates to an input function display device.
2. Related Art
Recently, a transparent conductive film has been developed in which a thin line pattern (conductive pattern) of metal or a conductive material is printed on a resin film, as a magnetic shield of a display or a transparent electrode for a resistive film touch panel. There are expectations for this as new technology to replace an ITO conductive film, for which there are concerns of depletion of earth's resources.
As a general related art of the touch panel and pen input, there is a resistive film type and a capacitive detection type using transparent electrodes. However, a display contrast deteriorates by about 10% due to transmittance or reflectance of the transparent electrodes. Particularly, in a mobile apparatus, there are many cases where a reflectance display body with low power consumption is used to extend a battery life, and display quality is drastically decreased by a decrease of transmittance by several %.
As the related art of preventing the decrease of the display performance, there is an optical type of detecting a position of pen input using a plurality of LED light sources and a photo sensor. However, in the optical type, since the LED or photo sensor is mounted on a peripheral portion of the display body and it is necessary to secure a light path, the display area becomes narrow and the thickness of the device is increased. In addition, there is a supersonic wave type which measures a retuning time of a supersonic wave to detect a position, but, as with the optical type, there is a problem in that the display area becomes narrow and the thickness of the device is increased.
JP-A-2005-302508 discloses a transparent conductive sheet having a conductive face formed of a transparent conductive film and a thin line structure of metal or alloy. JP-A-2006-330649 discloses a technique of detecting intensity of light by a display body driving TFT and inputting coordinates. JP-A-2002-196875 discloses an optical input technique in which a coordinate plate and a display body are partially shared. Furthermore, JP-A-63-70326 discloses a basic technique of an electromagnetic position detecting device. In this technique, a magnetic field generated from an electronic pen is detected by a plurality of loop antennas and an antenna substrate is provided under a display body.
The technique disclosed in JP-A-2005-302508 is proposed as the transparent conductive sheet for the resistive film touch panel, at least two opposed sheets are necessary, and there is a drawback that it may not be also used in a common electrode of a display body from the influence of noise.
The technique disclosed in JP-A-2006-330649 is limited to a specific display body or driving circuit, a lot of emission lightings are necessary in a periphery of a display body, and thus there are concerns about the narrowing of the display area and an increase of the thickness of the device.
The technique disclosed in JP-A-2002-196875 does not achieve sharing of an electrode layer with a coordinate plate and a display body similarly to the touch panel of the related art, and there are concerns of a decrease in transmittance. Even in JP-A-63-70326, it is difficult to reduce a size of a device, due to having a configuration in which an antenna substrate is provided under display body.